Bonnie L. Balzer

Perivascular epithelioid cell neoplasms of soft tissue and gynecologic origin : A clinicopathologic study of 26 cases and review of the literature

PEComas, occasionally associated with the tuberous sclerosis complex, are defined by the presence of perivascular epithelioid cells that coexpress muscle and melanocytic markers. This family of tumors includes angiomyolipoma (AML), clear cell sugar tumor of the lung (CCST), lymphangioleiomyomatosis (LAM), and very rare tumors in other locations. Because non-AML/non-LAM PEComas are extremely rare and their natural history and prognostic features undefined, we present our experience with 26 PEComas of soft tissue and the gynecologic tract, the largest series to date. We also performed a detailed review of the literature, with special attention to features predictive of clinical behavior. All PEComas exclusive of AML and LAM were retrieved from our consultation files. Immunohistochemistry for pan-cytokeratin (CK), S-100 protein, smooth muscle actins (SMA), desmin, vimentin, HMB45, Melan-A, microphthalmia transcription factor (MiTF), TFE3, CD117, and CD34 was performed. Clinical follow-up information was obtained. Fishers exact test was performed. The median patient age was 46 years (range, 15-97 years); there was a marked female predominance (22 females, 4 males). Sites of involvement included the omentum or mesentery (6 cases), uterus (4 cases), pelvic soft tissues (3 cases), abdominal wall (2 cases), uterine cervix (2 cases), and vagina, retroperitoneum, thigh, falciform ligament, scalp, broad ligament, forearm, shoulder, and neck (1 case each). The tumors ranged from 1.6 to 29 cm in size (median, 7.8 cm). Tumors were epithelioid (N = 9), spindled (N = 7), or mixed (N = 10). Multinucleated giant cells were present in 18 cases. High nuclear grade was noted in 10 cases, high cellularity in 7 cases, necrosis in 8 cases, and vascular invasion in 3 cases. Mitotic activity was 0 to 50 mitotic figures (MF)/50 high power fields (HPF) (median, 0 MF/50 HPF) with atypical MF in 6 cases. IHC results were: SMA (20/25), desmin (8/22), HMB45 (22/24), Melan-A (13/18), MITF (9/18), S-100 protein (8/24), CK (3/23), vimentin (12/14), TFE3 (5/17), c-kit (1/20), and CD34 (0/7). Clinical follow-up (24 of 26 patients, 92%; median, 30 months; range, 10-84 months) showed 3 local recurrences and 5 distant metastases. At last available clinical follow-up, 2 patients (8%) were dead of disease, 4 patients (17%) were alive with metastatic or unresectable local disease, and 18 patients (75%) were alive with no evidence of disease. No patient in our series had a history of tuberous sclerosis complex. Recurrence and/or metastasis was strongly associated tumor size > median size (8 cm), mitotic activity greater than 1/50 HPF, and necrosis. We conclude that PEComas of soft tissue and gynecologic origin may be classified as “benign,” “of uncertain malignant potential,” or “malignant.” Small PEComas without any worrisome histologic features are most likely benign. PEComas with nuclear pleomorphism alone (“symplastic”) and large PEComas without other worrisome features have uncertain malignant potential. PEComas with two or more worrisome histologic features should be considered malignant. Occasional PEComas express unusual markers, such as S-100 protein, desmin, and rarely CK. The role of TFE3 in PEComas should be further studied.

p16INK4A immunohistochemistry is superior to HPV in situ hybridization for the detection of high-risk HPV in atypical squamous metaplasia.

In situ hybridization (ISH) assays for high-risk human papillomavirus (HR-HPV) and immunohistochemical (IHC) assays for surrogate markers such as p16INK4A can be useful in detecting HR-HPV in cervical dysplasia, but the use of these markers in problematic cervical biopsies has not been well-established. We evaluated 3 chromogenic ISH assays (Ventana INFORM HPVII and HPVIII and DakoCytomation GenPoint) in conjunction with p16INK4A IHC and HPV polymerase chain reaction in a study set consisting of 12 low-grade squamous intraepithelial lesions, 16 high-grade squamous intraepithelial lesions, and 30 benign cervix samples. A test set of 28 cases of atypical squamous metaplasia were also evaluated withVentana HPVIII ISH and p16INK4A IHC. In the study set, the sensitivity of the DakoCytomation ISH assay (which detects HPV subtypes 16, 18, 31, 33, 35, 39, 45, 52, 56, 58, 59, and 68) was similar to the Ventana HPVII assay but less than that of the Ventana HPVIII ISH assay (both of which detect HPV subtypes 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 66) and less than p16INK4A IHC (55.6% vs. 53.6 vs. 69.2% vs. 82.1%). All HPV ISH assays exhibited 100% specificity. p16INK4A reactivity consisted of 2 patterns: focal strong and diffuse strong. Because focal strong p16INK4A reactivity was identified in benign squamous epithelium (6.7% cases) and dysplastic epithelium, it was considered an equivocal result and only diffuse strong reactivity was considered to be specific for the presence of HR-HPV. In the squamous intraepithelial lesions study set, the difference in sensitivity between Ventana HPVIII ISH and p16INK4A was not statistically significant. However, in the atypical squamous metaplasia test set cases, p16INK4A reactivity (focal strong and diffuse strong) was significantly more sensitive than Ventana HPVIII ISH in correlating with the presence of human papillomavirus as detected by polymerase chain reaction (83.3% vs. 33.3% P=0.004). Because focal strong p16INK4A reactivity is less specific, cases with this staining pattern are considered atypical and require further evaluation by other means. Overall, p16INK4A IHC is considered the best candidate for the initial assessment of cervical biopsies that are histologically indeterminate for dysplasia given its wide availability, comparative ease of interpretation, and high sensitivity and specificity.

Spontaneous regression of testicular germ cell tumors: an analysis of 42 cases.

Spontaneous regression of testicular germ cell tumors (GCTs) is a well-recognized phenomenon but has been incompletely characterized. Many pathologists are not familiar with the findings that support a diagnosis of a “burnt-out” primary in a patient with metastatic GCT. We therefore report the clinical, gross, and histologic findings in 42 cases of testicular GCT that showed either complete (26) or greater than 50% scarring (16). Thirty-seven patients (88%) had either known GCT metastasis or some residual testicular GCT, and none had treatment before orchiectomy. The patients were 17 to 67 years old, with a median of 32. Thirty presented with symptoms of metastasis, 7 with a testicular mass, 2 with elevated human chronic gonadotropin, and 1 with testicular pain. In 2 patients the presentation was unknown. Two patients had prior orchiopexy; another had an intraabdominal testis, and 2 others had prior contralateral seminoma (20 and 42 years previously). Gross descriptions in 37 cases identified white to tan scars, 0.6 to 2.4 cm, in 33. These were circumscribed in 16, with 15 of these having nodular or multinodular configurations and 1 a band-like appearance. In 9 cases the scar was ill defined or stellate, and in 8 cases no further details concerning the scar configuration were available. In 4 cases no scar was apparent; 2 of these had received intraoperative biopsy. Microscopically, all cases showed circumscribed to irregular foci of scarring, distinct from the adjacent parenchyma, in association with widespread testicular atrophy. Other common features were lymphoplasmacytic infiltrates in the scars (37/42) and “ghost” tubules in scars (31/42). Less common features in the scars included angiomatous foci (22/42), siderophages (15/42), and coarse intratubular calcifications (6/42); in the surrounding testis they included intratubular germ cell neoplasia, unclassified (IGCNU) (22/42), Leydig cell prominence (18/42), and necrosis (5/42). Tubular microliths occurred in 13 cases, 12 peripheral to the scar and 1 within it. Metastases in 31 cases were: pure seminoma (17, 3 with residual testicular seminoma), mixed GCT with seminoma (4, 3 with residual testicular seminoma), mixed nonseminomatous GCT (4, 3 with residual testicular GCT), pure embryonal carcinoma (2), pure teratoma (2, 1 with residual testicular teratoma), and pure yolk sac tumor (2). In 5 cases with clinically diagnosed metastases, there was no histologic documentation of the nature of the metastatic tumor. Testicular tumors in the remaining 6 cases having residual primaries without concomitant metastases were pure seminoma (3), mixed GCT with seminoma (2), and pure embryonal carcinoma (1). The most specific histologic findings of a regressed GCT are a distinct scar in association with either IGCNU or coarse intratubular calcifications; however, many cases lack the latter 2 features. In such cases additional features supportive of regressed GCT include testicular atrophy, microlithiasis and, in the scar, lymphoplasmacytic infiltrates and prominent vascularity. Ghost tubules in many scars are not evidence of a non-neoplastic process but likely reflect regression of tumors with intertubular growth. Intertubular growth is a common finding in seminoma, which is the single most frequent type of regressed GCT, occurring either in pure or mixed form in the metastases of 68% (21/31) of the cases and identifiable in 62% (10/16) of persistent testicular tumors. We conclude that regression of testicular GCTs shows a distinctive constellation of findings that usually permits its recognition. In contrast, nonspecific atrophy lacks distinct scars, and scars from non-neoplastic causes lack most of the associated findings seen in our cases.

Patterns of stromal invasion in ovarian serous tumors of low malignant potential (borderline tumors): a reevaluation of the concept of stromal microinvasion.

Stromal-epithelial patterns of invasion in serous tumors of the ovary have been subclassified as destructive and nondestructive. By definition, well-differentiated serous tumors featuring destructive stromal invasion are classified as low-grade serous carcinomas whereas those with either no stromal invasion or stromal microinvasion are classified as serous tumors of low malignant potential (S-LMP). The histologic features of stromal microinvasion in ovarian S-LMP have been addressed in a variety of studies, but controversy persists regarding diagnostic criteria and prognostic significance, particularly in patients with high-stage disease. In addition, a subset of otherwise typical S-LMP has patterns of invasion that are not classic destructive invasion and do not meet the current diagnostic criteria for stromal microinvasion because of either qualitative features or size restrictions. To further evaluate the full histologic spectrum of stromal-epithelial patterns of invasion in otherwise typical S-LMP, we examined a series of 60 ovarian S-LMP (34 FIGO stage I; 26 FIGO stages II, III, and IV) with stromal-epithelial alterations not meeting criteria for classic destructive invasion. This group of cases included those meeting the definition of microinvasion and a subset that would be excluded based on size measurements or unusual qualitative features, but did not exhibit significant stromal reaction. Five patterns of invasion were identified: individual eosinophilic cells and cell clusters, cribriform, simple and noncomplex branching papillae, inverted macropapillae, and micropapillae. Individual, discrete aggregates of invasive epithelium ranged from 1 to 12 mm (mean, 1.4 mm) in greatest linear dimension as measured by conventional methods. The number of discrete foci ranged from 1 to greater than 10; in 7 tumors (12%), the invasive foci were diffusely scattered throughout the stroma without discrete aggregates. These stromal-epithelial alterations were associated with disease progression and/or death due to disease in 9 of 50 (18%) patients with follow-up (mean, 92.5 mo) and were covariant with other adverse prognostic features (invasive implants, nodular lymph node aggregates, high stage, and unresectable disease). Disease progression was most strongly linked to the presence of micropapillae, but the majority of patients with adverse outcome had the more common, classic stromal-epithelial patterns associated with microinvasion (ie, individual cells, cell clusters, and simple papillae). Neither size of the largest contiguous aggregate nor extent of stromal involvement correlated with outcome. Classic microinvasion disproportionately occurred in patients presenting during pregnancy (P<0.0001), and was not associated with adverse outcome in that setting, but follow-up was limited. Based on the cumulative outcome data, the presence of stromal-epithelial patterns of invasion distinct from classic destructive invasion in otherwise typical S-LMP stratifies patients at long-term risk for disease progression, but does not warrant a diagnosis of carcinoma or a change in current management schemes. Maintaining classification as a serous tumor of low malignant potential (serous borderline tumor) with stromal invasion seems appropriate even in the presence of diffuse stromal involvement or discrete aggregates measuring greater than 3 (or 5) mm. As the stromal-epithelial alteration featuring micropapillae may represent a comparatively higher-risk lesion with a clinical course analogous to that of low-grade serous carcinoma, pathologists should identify this specific stromal-epithelial pattern in the diagnostic report until sufficient data is acquired to form more definitive conclusions regarding its prognosis.

Lymph node involvement in ovarian serous tumors of low malignant potential (borderline tumors): pathology, prognosis, and proposed classification.

The occurrence of regional lymph node involvement (LNI) in patients with primary ovarian serous tumors of low malignant potential (S-LMP), although well described in the literature, continues to be problematic. Most studies indicate that LNI is not associated with an adverse prognosis, but there has not been a comprehensive study addressing the histologic patterns of LNI, the importance, if any, of classifying the type of LNI (ie, as either noninvasive or invasive in analogy to peritoneal implant classification), or the presence and significance of associated endosalpingiosis. To further evaluate LNI in S-LMP, 74 patients with ovarian S-LMP and a lymph node biopsy or sampling were studied. Thirty-one of 74 patients had LNI in pelvic (18; 58%), mesenteric/omental (9; 29%), paraaortic (8; 26%), or supradiaphragmatic (2; 6%) lymph nodes. The number of involved nodes ranged from 1 to 20 (mean, 11.1). Four patterns of LNI were identified: individual cells, clusters of cells, and simple, nonbranching papillae (28 of 31; 90%); intraglandular (21 of 31; 68%); cells with prominent cytoplasmic eosinophilia (“eosinophilic cell” pattern) (16 of 31; 52%); and micropapillary pattern (5 of 31; 16%). LNI was diffuse in at least one lymph node in 13 patients (42%) and formed nodular aggregates greater than 1 mm in 6 patients (19%). Nodal endosalpingiosis was present in 58% of cases with LNI compared with 35% without LNI (P=0.06). There was no significant difference in survival for patients with LNI compared with patients without LNI. However, the presence of discrete nodular aggregates of epithelium greater than 1 mm in linear dimension without intervening lymphoid tissue was associated with a statistically significant decreased disease-free survival when compared with other patterns of LNI (P=0.02). Nodular aggregates were strongly associated with desmoplastic fibrous stromal reaction (P=0.001) and micropapillary architecture (0.02). There was also a trend for decreased survival among patients with LNI without associated endosalpingiosis (56%) compared with patients with LNI associated with endosalpingiosis (85%) and those with endosalpingiosis only (93%). This study suggests that patients with ovarian S-LMP may be further substratified into risk categories by the presence of nodular aggregates of S-LMP in lymph nodes, a feature that is more common in cases with micropapillary architecture and associated stromal reaction in the intranodal tumor. This high risk pattern of LNI may have a predictive value similar to invasive peritoneal implants and deserves independent evaluation in future studies of S-LMP.

Diagnostic implications of transcription factor Pax 2 protein and transmembrane enzyme complex carbonic anhydrase IX immunoreactivity in adult renal epithelial neoplasms.

Pax 2, expressed by metanephric mesenchyme is vital for renal tubule formation and development. Carbonic anhydrase IX (CA IX) is implicated in cell proliferation, adhesion, and invasion. Data regarding expression in renal epithelial tumors other than clear cell renal cell carcinoma (RCC) are limited, conflicting, from tissue microarrays, and do not encompass the entire spectrum or novel uncommon variants. Conventional sections from 200 renal tumors comprising clear cell RCC (n=30), oncocytoma (n=17), papillary RCC (n=30), chromophobe RCC (n=50), urothelial carcinomas (n=30), collecting duct carcinomas (n=5), renal tumors with Xp11.2 translocation (n=15), tubulocystic carcinoma (n=19), and mucinous tubular spindle cell carcinoma (n=4) were immunostained for Pax 2 and CA IX. Clear cell RCC (28/30, 93%), oncocytoma (17/17, 100%), papillary RCC (16/30, 53%), and mucinous tubular spindle cell carcinoma (3/4, 75%) demonstrated nuclear immunoreactivity with Pax 2, whereas the other subtypes were nonreactive. Clear cell RCC (30/30, 100%), urothelial carcinoma (27/30, 90%), papillary RCC (17/30, 57%), and renal tumors with Xp11.2 translocation (6/15, 40%) exhibited membranous immunoreactivity with CA IX, whereas the other subtypes were nonreactive. This suggests potential diagnostic utility of Pax 2 in distinction of (i) oncocytoma (positive) from chromophobe RCC (negative), (ii) clear cell RCC and papillary RCC (positive) from renal tumors with Xp11.2 translocation (negative), and (iii) high-grade clear cell RCC (positive) from urothelial carcinoma (negative). CA IX expression has potential diagnostic implications including (i) clear cell RCC (positive) versus chromophobe RCC (negative) and (ii) urothelial carcinoma (positive) versus collecting duct carcinoma (negative). These antibodies may reliably discriminate between clinically significant subtypes of RCC with overlapping cytoarchitectural features.

Primary Pulmonary Myxoid Sarcoma With EWSR1-CREB1 Fusion: A New Tumor Entity

We present clinicopathologic data on 10 pulmonary myxoid sarcomas, which are defined by distinctive histomorphologic features and characterized by a recurrent fusion gene, that appear to represent a distinct tumor entity at this site. The patients [7 female, 3 male; aged 27 to 67 y (mean, 45 y)] presented with local or systemic symptoms (n=5), symptoms from cerebral metastasis (1), or incidentally (2). Follow-up of 6 patients showed that 1 with brain metastasis died shortly after primary tumor resection, 1 developed a renal metastasis but is alive and well, and 4 are disease free after 1 to 15 years. All tumors involved pulmonary parenchyma, with a predominant endobronchial component in 8 and ranged from 1.5 to 4 cm. Microscopically, they were lobulated and composed of cords of polygonal, spindle, or stellate cells within myxoid stroma, morphologically reminiscent of extraskeletal myxoid chondrosarcoma. Four cases showed no or minimal atypia, 6 showed focal pleomorphism, and 5 had necrosis. Mitotic indices varied, with most tumors not exceeding 5/10 high-power fields. Tumors were immunoreactive for only vimentin and weakly focal for epithelial membrane antigen. Of 9 tumors, 7 were shown to harbor a specific EWSR1-CREB1 fusion by reverse transcription-polymerase chain reaction and direct sequencing, with 7 of 10 showing EWSR1 rearrangement by fluorescence in situ hybridization. This gene fusion has been described previously in 2 histologically and behaviorally different sarcomas: clear cell sarcoma-like tumors of the gastrointestinal tract and angiomatoid fibrous histiocytomas; however, this is a novel finding in tumors with the morphology we describe and that occur in the pulmonary region.

Cell Cycle Regulatory Markers in Uterine Atypical Leiomyoma and Leiomyosarcoma: Immunohistochemical Study of 68 Cases With Clinical Follow-up.

Cell cycle regulatory protein expression by immunohistochemical assay may have diagnostic utility in the distinction of uterine leiomyosarcoma from leiomyoma variants. p16, p21, p27, and p53 protein expression was evaluated by immunohistochemistry on 44 atypical leiomyomas (mean follow-up, 50.8 mo), 16 leiomyosarcomas (mean follow-up, 29.7 mo), and 8 cellular leiomyomas (mean follow-up, 22.6 mo). Nuclear staining was semiquantitatively scored on 1 representative section per case as negative (0%), focal (>0% to 33%), patchy (>33% to 66%), or diffuse (>66%). In addition, staining intensity was noted as weak, moderate, or strong. Proliferative index was gauged by Ki-67 and PHH3 immunohistochemical staining. One of 35 atypical leiomyoma patients with follow-up data developed an extrauterine recurrence 25.7 months after hysterectomy, whereas a second had intrauterine recurrence 24.9 months after myomectomy. Seven of 8 patients with leiomyosarcoma with follow-up had recurrence within the follow-up period, whereas there were no recurrences in patients with cellular leiomyoma. The Ki-67 proliferation index ranged from 0% to 25% in atypical leiomyoma (mean, 2%) and 6% to 50% in leiomyosarcoma (mean, 25%) with 0% to 10% in cellular leiomyoma (mean, 3%), whereas the PHH3 proliferation index ranged from 0% to 3% in atypical leiomyoma (mean, <1%) and 0% to 10% in leiomyosarcoma (mean, 2%) with 0% to 2% in cellular leiomyoma (mean, <1%). The atypical leiomyoma with extrauterine recurrence was diffusely positive for p21, but showed only weak focal (<33%) staining for all other cell cycle markers. Uterine atypical leiomyomas, cellular leiomyomas, and leiomyosarcomas demonstrate a heterogenous pattern of cell cycle regulatory protein expression. Caution should be exercised in distinguishing leiomyosarcoma from atypical leiomyoma variants on the basis of cell cycle protein expression alone. In our study, cell cycle markers were not useful for predicting recurrence in atypical leiomyoma.

Atypical leiomyomas of the uterus: a clinicopathologic study of 51 cases.

Atypical leiomyoma is a well-described smooth muscle neoplasm of the uterus. Only 1 study has addressed long-term clinical follow-up in a large series, and little is known about the adequacy of treatment by myomectomy. The surgical pathology archives were searched for consecutive cases of uterine atypical leiomyoma from 1992 to 2003. Glass slides were reviewed to confirm the diagnoses, and patient age, treatment modality, and clinical follow-up data were recorded. Fifty-one atypical leiomyomas with available glass slides and clinical follow-up data were identified. Thirty tumors exhibited diffuse, moderately to severely atypical cells, whereas 21 showed atypical cells in a more focal or patchy distribution. Twelve had ischemic-type necrosis. By the highest count method, 37 cases were found to have ⩽1 MF/10 HPF, 13 showed 1 to 3 MF/10 HPF, and 1 was nearly entirely necrotic precluding mitotic assessment. Among cases in which adjacent non-neoplastic tissue was well visualized, all were found to have pushing margins (46 cases). The average tumor size was 6.8 cm (median 6.5 cm; range, 0.7 to 14 cm). The average patient age was 42.5 years (median 42 y; range, 21 to 72 y). In all cases, the initial diagnostic procedure was hysterectomy (34) or myomectomy (17). Average follow-up was 42 months (range, 0.3 to 121.8 mo). Of those treated with hysterectomy, 1 had recurrent atypical leiomyoma in the retroperitoneum at 87.5 months, 1 died of other causes, and the remaining 32 (94%) were free of disease. Of the myomectomy group, 82% had no evidence of recurrent disease on follow-up: 2 had residual atypical leiomyoma in the subsequent hysterectomy specimen; and 1 underwent second myomectomy for atypical leiomyoma with 2 subsequent successful pregnancies. Atypical leiomyoma has a low rate of extrauterine, intra-abdominal recurrence (<2%) with a negligible risk for distant metastasis. Patients may be treated by myomectomy alone with successful pregnancy, but should be monitored for local intrauterine residual/recurrent disease.

Calcifying fibrous tumor: an unrecognized IgG4—related disease?

Calcifying fibrous tumor is a rare benign mass lesion characterized by bland spindle cells embedded in abundant collagenous matrix, interspersed dystrophic or psammomatous calcifications, and lymphoplasmacytic infiltrate. It shares several clinical and morphologic features with IgG4‐related disease, a newly recognized fibroinflammatory disorder. Characteristic histologic features of IgG4‐related lesions include dense fibrosis and abundant lymphoplasmacytic infiltrate, similar to calcifying fibrous tumor. They contain high numbers of IgG4‐positive plasma cells in the tissue. Patients also often have elevated serum IgG4 levels. We report the case of a patient with an ileal calcifying fibrous tumor that contained 69 IgG4‐positive plasma cells per high‐power field and an IgG4‐to‐IgG ratio of 56% in lesional plasma cells. The patients serum IgG4 level was 185 mg/dL, more than double the normal value. Altogether, these features suggest that calcifying fibrous tumor could be an unrecognized lesion of IgG4‐related disease.